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Old 05-12-12, 04:50 AM   #1
Myosmith
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Straighten bent aluminum RD hanger

I was recently given an almost new Schwinn S40 DSX MTB that sustained minor damage. The biggest problem is that the replaceable aluminum dropout/RD hanger is bent about 10-degrees sideways. It shows no cracking. Is it safe/practical to bend this back and realign it, or does it have to be replaced? I ask because the DSX is no longer in production and I don't know how easy it will be to get a new hanger.
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Old 05-12-12, 05:08 AM   #2
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So what's the options? Don't fix and don't use the bike? I'd try to find a replacement and straighten the hanger any way. Andy.
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Old 05-12-12, 05:17 AM   #3
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Have you looked at derailleurhanger.com?

FWIW, my experience is that I can often get away with bending an aluminum hanger back once, maybe twice if the bends aren't so bad. There's no harm in trying.
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Old 05-12-12, 06:57 AM   #4
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In my experience derailer hangers, if re-bent carefully and not over bent, can be done 2-3 times. Be sure you use the proper tool.

+1 on derailleurhanger.com.
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Old 05-12-12, 07:32 AM   #5
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So what's the options? Don't fix and don't use the bike?
Thanks all for the advice. I have looked at derailleurhanger.com and didn't see this model listed, but from what I understand the same hanger was used on several models so it might still be there. I'll give them a call. Replacement is definately the surest option, I just wanted to know how safe it was to use an aluminum hanger that had been bent and straightened. Yeah, not fixing and not using the bike is an option of I cannot find a replacement hanger and if (though this doesn't sound like the case) rebending the hanger would be unsafe. Failure of a derailleur hanger can mean derailleur and chain into spokes which could result in a major crash, especially on a rough downhill. I know there are always risks, but I won't ride a bike if I know there is something wrong with it that could result in severe injury.

The first LBS I checked with didn't sound promising, but the second said they would probably be able to solve the problem, so I might just leave it in their hands. Hopefully we can find the right hanger and life will be good again.
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Old 05-12-12, 07:57 AM   #6
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IMO you'd be unlucky to be injured via a busted hanger.

The derailleur could maybe go into the spokes, come around and smack into the chainstay causing a rear wheel lockup, but even so, that shouldn't be the end of the world unless the timing is particularly awful.

The break wouldn't be likely to happen either; if it was about to break, you could tell by looking at it, and you wouldn't decide to use it. It wouldn't get any worse until it was bent again.
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Old 05-12-12, 08:06 AM   #7
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go where the Alignment tool is , it has to be right to get the indexing to click in.
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Old 05-12-12, 09:23 AM   #8
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Originally Posted by wmodavis View Post
Be sure you use the proper tool.
How many rear cogs do you have?

I've had good luck "eyeballing" the derailleur hanger back into line on a 7-speed and getting accurate indexing afterward. For 9-speed and above, I have to use a gauge.

If you're "eyeballing" be sure to keep the derailleur bolter into the hanger. Otherwise you may ovalize the threaded mounting hole.
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Old 05-12-12, 01:22 PM   #9
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heat and bend, 10 degrees isn't that big of a deal.

Use a rubber/wooden/plastic mallet on a smooth surface with a few light taps.
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Old 05-12-12, 02:00 PM   #10
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They're replaceable for a reason, I can't believe you're even considering this. Back in the day if the hanger on an aluminum frame without a replaceable hanger bent, even 10 degrees, the frame would be thrashed. Aluminum can't be reliably bent back.

You either need to find the direct replacement or come up with a kludge to get another hanger on there. This hanger is toast.
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Old 05-12-12, 03:20 PM   #11
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Get a replacement hanger. While you are at it, get a spare for next time.
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Old 05-12-12, 08:05 PM   #12
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As mentioned above, my preferred option is to replace the hanger. The purpose of this thread was to determine if, in the event that a suitable replacement can't be found, straightening the original hanger was an option. Got opinions on both sides of the fence on that one.
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Old 05-12-12, 08:13 PM   #13
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It's not an option, well not for long, and when it stops being an option, you run the risk of needing a new RD, wheel, chain, face, collar bone and... seriously, don't even try and bend it back, it'll probably shear on you just by trying to bend it back. Aluminum doesn't bend for crap, it just shears. What the hell, try it, but use a real critical eye to look for the cracks and stress marks.

Another option is a hanger like the ones that used to come on crappier 10 speeds that has the little slot for the axle, you'd still need to rig something for the second bolt (without this, it'll just spin around the axle) that used to slide into the long dropout. Maybe a rack hole, maybe not.

Something like this-
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Old 05-12-12, 08:34 PM   #14
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Aluminum doesn't bend for crap, it just shears.
There are zillions of different grades of ally, and many of them will cope with being bent back ten degrees once. Although it might be that hangers tend to be made of something too brittle.
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What the hell, try it, but use a real critical eye to look for the cracks and stress marks.
This. if it doesn't cause a bunch of little surface cracks, you're good to go, IMO. Even if you get a few tiny ones, the part would almost certainly be strong enough to keep doing its job until it gets bent again.

As an aside, how's this for weird - I have an ally frame that has a stainless hanger. I'm not sure what kind of sense that's supposed to make... in the area around the QR, it's sandwiched between the dropout. Maybe it's got some sort of fancy metallurgy going on whereby it's meant to crack off where it steps out to the width of the dropout, but I can see it more likely causing carnage and defeating the purpose. Odd, no?
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